The present invention relates to an internal combustion engine, fuel properties estimating apparatus and process.
A vehicle known as flexible fuel vehicle (FFV) can run on a blend fuel of alcohol and gasoline as well as on gasoline. Alcohol fuel requires adjustment of a fuel injection quantity in accordance with an alcohol concentration in the fuel because the number of atoms of C (carbon) is different from that of ordinary gasoline fuel. Therefore, an engine system as shown in a Published Japanese Patent Application Publication No. H05(1993)-163992 is arranged to sense an alcohol concentration with an alcohol concentration sensor provided in a fuel tank and to estimate the alcohol concentration from an average value of air-fuel ratio feedback correction coefficient in the case of a failure of the alcohol concentration sensor.